samedi 10 septembre 2016

GSLV-F05 is the tenth flight of India's Geosynchronous Satellite Launch Vehicle (GSLV), launching INSAT-3DR, an advanced weather satellite, weighing 2211 kg into a Geostationary Transfer Orbit (GTO). GSLV is designed to inject 2 - 2.5 Tonne class of satellites into GTO. The launch took place from the Second Launch Pad at Satish Dhawan Space Centre SHAR (SDSC SHAR), Sriharikota on September 08, 2016.

GSLV-F05 Lift off

GSLV-F05 flight is significant since it is the first operational flight of GSLV carrying Cryogenic Upper Stage (CUS). The indigenously developed CUS was carried on-board for the fourth time during a GSLV flight in the GSLV-F05 flight.

INSAT-3DR

GSLV-F05 vehicle is configured with all its three stages including the CUS similar to the ones successfully flown during the previous GSLV-D5 and D6 missions in January 2014 and August 2015. GSLV-D5 and D6 successfully placed GSAT-14 and GSAT-6 satellites carried on-board in the intended GTOs accurately.

The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA's Curiosity Mars rover, which is currently exploring the "Murray Buttes" region of lower Mount Sharp. The new images arguably rival photos taken in U.S. National Parks.

Curiosity took the images with its Mast Camera (Mastcam) on Sept. 8. The rover team plans to assemble several large, color mosaics from the multitude of images taken at this location in the near future.

Image above: The rim of Gale Crater is visible in the distance, through the dusty haze, in this Curiosity view of a sloping hillside on Mount Sharp. Image Credits: NASA/JPL-Caltech/MSSS.

"Curiosity's science team has been just thrilled to go on this road trip through a bit of the American desert Southwest on Mars," said Curiosity Project Scientist Ashwin Vasavada, of NASA's Jet Propulsion Laboratory, Pasadena, California.

The Martian buttes and mesas rising above the surface are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed.

"Studying these buttes up close has given us a better understanding of ancient sand dunes that formed and were buried, chemically changed by groundwater, exhumed and eroded to form the landscape that we see today," Vasavada said.

The new images represent Curiosity's last stop in the Murray Buttes, where the rover has been driving for just over one month. As of this week, Curiosity has exited these buttes toward the south, driving up to the base of the final butte on its way out. In this location, the rover began its latest drilling campaign (on Sept. 9). After this drilling is completed, Curiosity will continue farther south and higher up Mount Sharp, leaving behind these spectacular formations.

Curiosity landed near Mount Sharp in 2012. It reached the base of the mountain in 2014 after successfully finding evidence on the surrounding plains that ancient Martian lakes offered conditions that would have been favorable for microbes if Mars has ever hosted life. Rock layers forming the base of Mount Sharp accumulated as sediment within ancient lakes billions of years ago.

On Mount Sharp, Curiosity is investigating how and when the habitable ancient conditions known from the mission's earlier findings evolved into conditions drier and less favorable for life.

Image above: This view from Curiosity shows a dramatic hillside outcrop with sandstone layers that scientists refer to as "cross-bedding." Image Credits: NASA/JPL-Caltech/MSSS.

vendredi 9 septembre 2016

(Highlights: Week of Aug. 29, 2016) - It was a busy week on the International Space Station with a spacewalk and the preparation for NASA astronaut Jeff Williams' return home. Before he finished his six-month stay, Williams and other crew members performed multiple tests and sample collections on themselves as part of important research on humans that could change the way we address health issues on Earth.

Image above: This photograph of the Japanese Experiment Module (JEM) section of the International Space Station was captured during a spacewalk conducted by NASA astronauts Jeff Williams and Kate Rubins. Image Credit: NASA.

Human research is an important part of the space station mission, helping determine how the body reacts to long stays in microgravity. Williams made final measurements for the investigation Defining the Relationship Between Biomarkers of Oxidative and Inflammatory Stress and the Risk for Atherosclerosis in Astronauts During and After Long-duration Spaceflight (Cardio Ox). This study will look for signs of oxidative and inflammatory stress on cardiovascular health during and after spaceflight. Williams took ultrasound images of his heart upon arrival at the station and has taken a few more just days before his scheduled departure on Sept. 6. These images will be compared to more ultrasounds taken before his flight and others that will be taken soon after his return home. The investigation will define the cardiovascular risks associated with long journeys in space, help define treatments while in space and track the health care of space travelers in the years after their return home. It could also help identify new markers for those at risk for cardiovascular disease on Earth.

NASA astronaut Kate Rubins completed her third session of the Skin-B investigation. The ESA (European Space Agency) investigation will improve understanding of skin aging, which is slow on Earth but accelerated in space. It will provide insight into the aging process in other similar bodily tissues and could help scientists identify the impacts on astronauts during future long-duration missions beyond low-Earth orbit where environmental conditions are more challenging.

Image above: This image captured as the International Space Station crossed over the west coast of Africa shows the Cloud-Aerosol Transport System (CATS) mounted to the station on the right and a visible dust cloud extending for miles over the Atlantic Ocean. CATS captures in-depth data of clouds -- dust and condensed vapor -- to help scientists create a better model of Earth's climate system and predict climate changes more precisely. Image Credit: NASA.

Rubins measured the hydration level of her skin’s outer layer, the skin barrier function and the skin surface topography of her forearm. The data will be compared to measurements performed before she began her stay on the space station and those collected during her mission on orbit. Data gathered on the station can provide insight into the mechanisms by which all organs covered with epithelial and connective tissue adapt and age over time and under the physical stress imposed by the microgravity environment. Gaining an understanding of how biological tissue can change should allow for better diagnoses of skin problems and treatment on Earth.

The Cloud-Aerosol Transport System (CATS) -- installed on the outside of the space station -- continued successful Earth observations by capturing images of dust clouds off the coast of Africa. The CATS light detection and ranging system measures the location, composition and distribution of pollution, dust, smoke, aerosols and other particulates in the atmosphere using lasers. A better understanding of cloud and aerosol coverage over a long period will help scientists create a better model of Earth's climate system and predict climate changes more precisely.

Image above: NASA astronaut Jeff Williams takes a moment to capture a "space selfie" while on his final spacewalk outside the International Space Staiton. He and fellow astronaut Kate Rubins were stowing an unused thermal radiator and installing external high-definition cameras to provide better quality views of external activities and approaching spacecraft. Image Credit: NASA.

Progress was made on other investigations and facilities this week, including Mouse Epigenetics, ISS Ham, Biomolecule Sequencer, and the Multi-Purpose Small Payload Rack.

This shot from the NASA/ESA Hubble Space Telescope shows a maelstrom of glowing gas and dark dust within one of the Milky Way’s satellite galaxies, the Large Magellanic Cloud (LMC).

This stormy scene shows a stellar nursery known as N159, an HII region over 150 light-years across. N159 contains many hot young stars. These stars are emitting intense ultraviolet light, which causes nearby hydrogen gas to glow, and torrential stellar winds, which are carving out ridges, arcs, and filaments from the surrounding material.

At the heart of this cosmic cloud lies the Papillon Nebula, a butterfly-shaped region of nebulosity. This small, dense object is classified as a High-Excitation Blob, and is thought to be tightly linked to the early stages of massive star formation.

Hubble orbiting Earth

N159 is located over 160,000 light-years away. It resides just south of the Tarantula Nebula (heic1402), another massive star-forming complex within the LMC. This image comes from Hubble’s Advanced Camera for Surveys. The region was previously imaged by Hubble’s Wide Field Planetary Camera 2, which also resolved the Papillon Nebula for the first time.

Squeezing out unique scientific observations until the very end, Rosetta’s thrilling mission will culminate with a descent on 30 September towards a region of active pits on the comet’s ‘head’.

The region, known as Ma’at, lies on the smaller of the two lobes of Comet 67P/Churyumov–Gerasimenko. It is home to several active pits more than 100 m in diameter and 50–60 m in depth – where a number of the comet’s dust jets originate.

Rosetta’s last week at the comet

The walls of the pits also exhibit intriguing metre-sized lumpy structures called ‘goosebumps’, which scientists believe could be the signatures of early ‘cometesimals’ that assembled to create the comet in the early phases of Solar System formation.

Rosetta will get its closest look yet at these fascinating structures on 30 September: the spacecraft will target a point adjacent to a 130 m-wide, well-defined pit that the mission team has informally named Deir el-Medina, after a structure with a similar appearance in an ancient Egyptian town of the same name.

Like the archaeological artefacts found inside the Egyptian pit that tell historians about life in that town, the comet’s pit contains clues to the geological history of the region.

Rosetta will target a point very close to Deir el-Medina, within an ellipse about 700 x 500 m.

Since 9 August, Rosetta has been flying elliptical orbits that bring it progressively closer to the comet – on its closest flyby, it may come within 1 km of the surface, closer than ever before.

Rosetta’s planned impact site

“Although we’ve been flying Rosetta around the comet for two years now, keeping it operating safely for the final weeks of the mission in the unpredictable environment of this comet and so far from the Sun and Earth, will be our biggest challenge yet,” says Sylvain Lodiot, ESA’s spacecraft operations manager.

“We are already feeling the difference in gravitational pull of the comet as we fly closer and closer: it is increasing the spacecraft’s orbital period, which has to be corrected by small manoeuvres. But this is why we have these flyovers, stepping down in small increments to be robust against these issues when we make the final approach.”

The final flyover will be complete on 24 September. Then a short series of manoeuvres needed to line Rosetta up with the target impact site will be executed over the following days as it transfers from flying elliptical orbits around the comet onto a trajectory that will eventually take it to the comet’s surface on 30 September.

The collision manoeuvre will take place in the evening of 29 September, initiating the descent from an altitude of about 20 km. Rosetta will essentially free-fall slowly towards the comet in order to maximise the number of scientific measurements that can be collected and returned to Earth before its impact.

A number of Rosetta’s scientific instruments will collect data during the descent, providing unique images and other data on the gas, dust and plasma very close to the comet. The exact complement of instruments and their operational timeline remains to be fixed, because it depends on constraints of the final planned trajectory and the data rate available on the day.

Understanding Rosetta’s final signal

The impact is predicted to occur within 20 minutes of 10:40 GMT, with uncertainties linked to the exact trajectory of Rosetta on the day, and the influence of gravity close to the comet. Taking into account the additional 40 minute signal travel time between Rosetta and Earth on 30 September, this means that the confirmation of impact is expected at ESA’s mission control in Darmstadt, Germany, within 20 minutes of 11:20 GMT (13:20 CEST). The times will be updated as the trajectory is refined.

Mirroring Rosetta’s wake-up from deep space hibernation in January 2014, where a rising peak at the right frequency confirmed that the spacecraft was alive and transmitting its carrier signal, mission controllers will see that peak disappear for a final time once Rosetta impacts. It will not be possible to retrieve any data after this time.

“Last month we celebrated two thrilling years since arriving at the comet, and also a year since the comet’s closest approach to the Sun along its orbit,” says Matt Taylor, ESA’s Rosetta project scientist.

“It’s hard to believe that Rosetta’s incredible 12.5 year odyssey is almost over, and we’re planning the final set of science operations, but we are certainly looking forward to focusing on analysing the reams of data for many decades to come.”

“This pioneering mission may be coming to an end, but it has certainly left its mark in the technical, scientific and public spheres as being one of outstanding success, with incredible achievements contributing to the current and future understanding of our Solar System,” adds Patrick Martin, ESA’s Rosetta mission manager.

More information:

All times and details regarding the end of mission are preliminary and subject to change as Rosetta’s final trajectory is refined. Even on the day, timings will have uncertainties owing to circumstances at the comet beyond the control of the mission team.

For further information, you can consult the end-of-mission FAQ: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_s_grand_finale_frequently_asked_questions

Application for accredited media and social media representatives to attend the event in Darmstadt on 30 September is possible via the Call for Media. Science journalists will also be eligible to attend a briefing on 29 September focusing on the scientific results of the mission. Livestream details will also be provided nearer the time.

An ESA Hangout on Air is planned for Monday 19 September 12:00 GMT (1400 CEST) to present the latest information regarding the details of the last week’s operations and the story of the search behind finding Philae. More details will be provided soon.

jeudi 8 septembre 2016

NASA's first asteroid sampling mission launched into space at 7:05 p.m. EDT Thursday from Cape Canaveral Air Force Station in Florida, beginning a journey that could revolutionize our understanding of the early solar system.

Image above: A United Launch Alliance Atlas V rocket lifts off from Space Launch Complex 41 at Cape Canaveral Air Force Station carrying NASA’s Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer, or OSIRIS-REx spacecraft on the first U.S. mission to sample an asteroid, retrieve at least two ounces of surface material and return it to Earth for study.Liftoff was at 7:05 p.m. EDT. Image Credit: NASA.

“Today, we celebrate a huge milestone for this remarkable mission, and for this mission team,” said NASA Administrator Charles Bolden. “We’re very excited about what this mission can tell us about the origin of our solar system, and we celebrate the bigger picture of science that is helping us make discoveries and accomplish milestones that might have been science fiction yesterday, but are science facts today.”

First U.S. Sample Return Mission to an Asteroid Launches

The Origins, Spectral Interpretation, Resource Identification, Security-Regolith Explorer (OSIRIS-REx) spacecraft is designed to rendezvous with, study, and return a sample of the asteroid Bennu to Earth. Asteroids like Bennu are remnants from the formation of our solar system more than 4.5 billion years ago. Scientists suspect that asteroids may have been a source of the water and organic molecules for the early Earth and other planetary bodies. An uncontaminated asteroid sample from a known source would enable precise analyses, providing results far beyond what can be achieved by spacecraft-based instruments or by studying meteorites.

OSIRIS-REx separated from its United Launch Alliance Atlas V rocket at 8:04 p.m. The solar arrays deployed and are now powering the spacecraft.

First stage separation. Image Credit: NASA TV

“With today’s successful launch, the OSIRIS-REx spacecraft embarks on a journey of exploration to Bennu,” said Dante Lauretta, OSIRIS-REx principal investigator at the University of Arizona, Tucson. “I couldn’t be more proud of the team that made this mission a reality, and I can’t wait to see what we will discover at Bennu.”

In 2018, OSIRIS-REx will approach Bennu – which is the size of a small mountain – and begin an intricate dance with the asteroid, mapping and studying Bennu in preparation for sample collection. In July 2020, the spacecraft will perform a daring maneuver in which its 11-foot arm will reach out and perform a five-second “high-five” to stir up surface material, collecting at least 2 ounces (60 grams) of small rocks and dust in a sample return container. OSIRIS-REx will return the sample to Earth in September 2023, when it will then be transported to NASA’s Johnson Space Center in Houston for examination.

The OSIRIS-REx mission will be the first U.S. mission to carry samples from an asteroid back to Earth and the largest sample returned from space since the Apollo era.

"It’s satisfying to see the culmination of years of effort from this outstanding team,” said Mike Donnelly, OSIRIS-REx project manager at NASA's Goddard Space Flight Center in Greenbelt, Maryland. “We were able to deliver OSIRIS-REx on time and under budget to the launch site, and will soon do something that no other NASA spacecraft has done – bring back a sample from an asteroid.”

Goddard provides overall mission management, systems engineering and the safety and mission assurance for OSIRIS-REx. The University of Arizona leads the science team and observation planning and processing. Lockheed Martin Space Systems in Denver built the spacecraft. OSIRIS-REx is the third mission in NASA’s New Frontiers Program. NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the agency’s New Frontiers Program for its Science Mission Directorate in Washington. Launch and countdown management is the responsibility of NASA’s Kennedy Space Center in Florida.

Using NASA’s Chandra X-ray Observatory and other X-ray observatories, astronomers have found evidence for what is likely one of the most extreme pulsars, or rotating neutron stars, ever detected. The source exhibits properties of a highly magnetized neutron star, or magnetar, yet its deduced spin period is thousands of times longer than any pulsar ever observed.

For decades, astronomers have known there is a dense, compact source at the center of RCW 103, the remains of a supernova explosion located about 9,000 light years from Earth. This composite image shows RCW 103 and its central source, known officially as 1E 161348-5055 (1E 1613, for short), in three bands of X-ray light detected by Chandra. In this image, the lowest energy X-rays from Chandra are red, the medium band is green, and the highest energy X-rays are blue. The bright blue X-ray source in the middle of RCW 103 is 1E 1613. The X-ray data have been combined with an optical image from the Digitized Sky Survey.

Observers had previously agreed that 1E 1613 is a neutron star, an extremely dense star created by the supernova that produced RCW 103. However, the regular variation in the X-ray brightness of the source, with a period of about six and a half hours, presented a puzzle. All proposed models had problems explaining this slow periodicity, but the main ideas were of either a spinning neutron star that is rotating extremely slowly because of an unexplained slow-down mechanism, or a faster-spinning neutron star that is in orbit with a normal star in a binary system.

On June 22, 2016, an instrument aboard NASA’s Swift telescope captured the release of a short burst of X-rays from 1E 1613. The Swift detection caught astronomers’ attention because the source exhibited intense, extremely rapid fluctuations on a time scale of milliseconds, similar to other known magnetars. These exotic objects possess the most powerful magnetic fields in the Universe –trillions of times that observed on the Sun – and can erupt with enormous amounts of energy.

Seeking to investigate further, a team of astronomers led by Nanda Rea of the University of Amsterdam quickly asked two other orbiting telescopes – NASA’s Chandra X-ray Observatory and Nuclear Spectroscopic Telescope Array, or NuSTAR – to follow up with observations.

New data from this trio of high-energy telescopes, and archival data from Chandra, Swift and ESA’s XMM-Newton confirmed that 1E 1613 has the properties of a magnetar, making it only the 30th known. These properties include the relative amounts of X-rays produced at different energies and the way the neutron star cooled after the 2016 burst and another burst seen in 1999. The binary explanation is considered unlikely because the new data show that the strength of the periodic variation in X-rays changes dramatically both with the energy of the X-rays and with time. However, this behavior is typical for magnetars.

Chandra X-ray Observatory. Image Credits: NASA/CXC

But the mystery of the slow spin remained. The source is rotating once every 24,000 seconds (6.67 hours), much slower than the slowest magnetars known until now, which spin around once every 10 seconds. This would make it the slowest spinning neutron star ever detected.

Astronomers expect that a single neutron star will be spinning quickly after its birth in the supernova explosion and will then slow down over time as it loses energy. However, the researchers estimate that the magnetar within RCW 103 is about 2,000 years old, which is not enough time for the pulsar to slow down to a period of 24,000 seconds by conventional means.

While it is still unclear why 1E 1613 is spinning so slowly, scientists do have some ideas. One leading scenario is that debris from the exploded star has fallen back onto magnetic field lines around the spinning neutron star, causing it to spin more slowly with time. Searches are currently being made for other very slowly spinning magnetars to study this idea in more detail.

Another group, led by Antonino D'Aì at the National Institute of Astrophysics (INAF) in Palermo, Italy, monitored 1E 1613 in X-rays using Swift and in the near-infrared and visible light using the 2.2-meter telescope at the European Southern Observatory at La Silla, Chile, to search for any low-energy counterpart to the X-ray burst. They also conclude that 1E 1613 is a magnetar with a very slow spin period.

A paper describing the findings of Rea’s team appears in the September 2, 2016, issue of The Astrophysical Journal Letters and is available online (http://lanl.arxiv.org/abs/1607.04107). The authors of that paper are Nanda Rea (University of Amsterdam and IEEC-CSIC, Spain), A. Borghese (Univ. of Amsterdam), P. Esposito (Univ. of Amsterdam), F. Coti Zelati (Univ. of Amsterdam, INAF, Insubria), M. Bachetti (INAF), G. L. Israel (INAF), A. De Luca (INAF).

A paper describing the findings of D'Aì's team has been accepted for publication by Monthly Notices of the Royal Astronomical Society and is also available online: https://arxiv.org/abs/1607.04264

NuSTAR is a Small Explorer mission led by the California Institute of Technology in Pasadena and managed by NASA's Jet Propulsion Laboratory, also in Pasadena, for NASA's Science Mission Directorate in Washington.

NASA's Swift satellite was launched in November 2004 and is managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Image above: These nebulae seen by NASA's Spitzer Space Telescope, at left, may resemble two versions of the starship Enterprise from "Star Trek," overlaid at right. Image Credits: NASA/JPL-Caltech.

Just in time for the 50th anniversary of the TV series "Star Trek," which first aired September 8th,1966, a new infrared image from NASA's Spitzer Space Telescope may remind fans of the historic show.

Since ancient times, people have imagined familiar objects when gazing at the heavens. There are many examples of this phenomenon, known as pareidolia, including the constellations and the well-known nebulae named Ant, Stingray and Hourglass.

On the right of the image, with a little scrutiny, you may see hints of the saucer and hull of the original USS Enterprise, captained by James T. Kirk, as if it were emerging from a dark nebula. To the left, its "Next Generation" successor, Jean-Luc Picard's Enterprise-D, flies off in the opposite direction.

Astronomically speaking, the region pictured in the image falls within the disk of our Milky Way galaxy and displays two regions of star formation hidden behind a haze of dust when viewed in visible light. Spitzer's ability to peer deeper into dust clouds has revealed a myriad of stellar birthplaces like these, which are officially known only by their catalog numbers, IRAS 19340+2016 and IRAS19343+2026.

Trekkies, however, may prefer using the more familiar designations NCC-1701 and NCC-1701-D. Fifty years after its inception, Star Trek still inspires fans and astronomers alike to boldly explore where no one has gone before.

Spitzer Space Telescope. Image Credits: NASA/JPL-Caltech

This image was assembled using data from Spitzer's biggest surveys of the Milky Way, called GLIMPSE and MIPSGAL. Light with a wavelength of 3.5 microns is shown in blue, 8.0 microns in green, and 24 microns in red. The green colors highlight organic molecules in the dust clouds, illuminated by starlight. Red colors are related to thermal radiation emitted from the very hottest areas of dust.

mercredi 7 septembre 2016

Animation above: This animated gif of asteroid 2016 RB1’s close approach to Earth was imaged by astronomer Gianluca Masi on the evening of Sept. 6, 2016, using the Virtual Telescope located in Ceccano, Central Italy. Animation Credits: VT/Masi.

A small asteroid designated 2016 RB1 safely flew past Earth today at 10:20 a.m. PDT (1:20 p.m. EDT / 17:20 UTC) at a distance of about 25,000 miles (40,000 kilometers, or just less than 1/10th the distance of Earth to the moon). Because the asteroid’s orbit carried it below (or over) Earth’s south pole, it did not pass within the orbits of communication or weather satellites. 2016 RB1 is estimated to be between 25 to 50 feet (7 and 16 meters) in diameter. It is the closest the space rock will come to Earth for at least the next half century.

Asteroid 2016 RB1 was discovered on Sept. 5, 2016, by astronomers using the 60-inch Cassegrain reflector telescope of the Catalina Sky Survey, located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona -- a project of NASA'S NEO Observations Program in collaboration with the University of Arizona.

The Center for NEO Studies website has a complete list of recent and upcoming close approaches, as well as all other data on the orbits of known NEOs (near-Earth objects), so scientists and members of the media and public can track information on known objects.

New scenes from a frigid alien landscape are coming to light in recent radar images of Saturn's largest moon, Titan, from NASA's Cassini spacecraft.

Cassini obtained the views during a close flyby of Titan on July 25, when the spacecraft came as close as 607 miles (976 kilometers) from the giant moon. The spacecraft's radar instrument is able to penetrate the dense, global haze that surrounds Titan, to reveal fine details on the surface.

Dunes of Shangri-La on Saturn's Moon Titan

Video above: NASA's Cassini spacecraft has radar vision that allows it to peer through the haze that surrounds Saturn's largest moon, Titan. This video focuses on Shangri-la, a large, dark area on Titan filled with dunes. The long, linear dunes are thought to be comprised of grains derived from hydrocarbons that have settled out of Titan's atmosphere. Video Credits: NASA Jet Propulsion Laboratory.

One of the new views (along with a short video) shows long, linear dunes, thought to be comprised of grains derived from hydrocarbons that have settled out of Titan's atmosphere. Cassini has shown that dunes of this sort encircle most of Titan's equator. Scientists can use the dunes to learn about winds, the sands they're composed of, and highs and lows in the landscape.

"Dunes are dynamic features. They're deflected by obstacles along the downwind path, often making beautiful, undulating patterns," said Jani Radebaugh, a Cassini radar team associate at Brigham Young University in Provo, Utah.

Another new image shows an area nicknamed the "Xanadu annex" earlier in the mission by members of the Cassini radar team. Cassini's radar had not previously obtained images of this area, but earlier measurements by the spacecraft suggested the terrain might be quite similar to the large region on Titan named Xanadu.

First imaged in 1994 by NASA's Hubble Space Telescope, Xanadu was the first surface feature to be recognized on Titan. While Hubble was able to see Xanadu's outline, the annex area went unnoticed.

The new Cassini image reveals that the Xanadu annex is, indeed, made up of the same type of mountainous terrains observed in Xanadu and scattered across other parts of Titan.

"This 'annex' looks quite similar to Xanadu using our radar, but there seems to be something different about the surface there that masks this similarity when observing at other wavelengths, as with Hubble," said Mike Janssen, also a JPL member of the radar team. "It's an interesting puzzle."

Xanadu -- and now its annex -- remains something of a mystery. Elsewhere on Titan, mountainous terrain appears in small, isolated patches, but Xanadu covers a large area, and scientists have proposed a variety of theories about its formation.

"These mountainous areas appear to be the oldest terrains on Titan, probably remnants of the icy crust before it was covered by organic sediments from the atmosphere," said Rosaly Lopes, a Cassini radar team member at JPL. "Hiking in these rugged landscapes would likely be similar to hiking in the Badlands of South Dakota."

The July 25 flyby was Cassini's 122nd encounter with Titan since the spacecraft's arrival in the Saturn system in mid-2004. It was also the last time Cassini's radar will image terrain in the far southern latitudes of Titan.

"If Cassini were orbiting Earth instead of Saturn, this would be like getting our last close view of Australia," said Stephen Wall, deputy lead of the Cassini radar team at NASA's Jet Propulsion Laboratory in Pasadena, California.

Cassini Titan flyby. Image Credits: NASA/JPL-Caltech

Cassini's four remaining Titan flybys will focus primarily on the liquid-filled lakes and seas in Titan's far north. The mission will begin its finale in April 2017, with a series of 22 orbits that plunge between the planet and its icy rings.

The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. JPL, a division of Caltech in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the U.S. and several European countries.

Rosetta's dust-analysing COSIMA (COmetary Secondary Ion Mass Analyser) instrument has made the first unambiguous detection of solid organic matter in the dust particles ejected by Comet 67P/Churyumov-Gerasimenko, in the form of complex carbon-bearing molecules.

Image above: Optical image of two of the dust grains collected and analysed by COSIMA, named Kenneth and Juliette, which show the signature of carbon-based organics. Images Credit: ESA/Rosetta/MPS for COSIMA Team MPS/CSNSM/UNIBW/TUORLA/IWF/IAS/ESA/BUW/MPE/LPC2E/LCM/FMI/UTU/LISA/UOFC/vH&S/ Fray et al. (2016).

While organics had already been detected in situ on the comet's surface by instruments on-board Philae and from orbit by Rosetta's ROSINA, those were both in the form of gases resulting from the sublimation of ices. By contrast, COSIMA has made its detections in solid dust.

Their presence was only ever hinted at in previous comet missions, which flew by their targets at high speed and, as a result, disrupted the particles, making characterisation challenging. But Rosetta is orbiting Comet 67P/C-G and can catch dust particles moving at low speed.

"Our analysis reveals carbon in a far more complex form than expected," remarked Hervé Cottin, one of the authors of the paper reporting the result that is published in Nature today. "It is so complex, we can't give it a proper formula or a name!"

The organic signatures of seven particles are presented in the paper, which the COSIMA team say are representative of the two hundred plus grains analysed so far.

The carbon is found to be mixed with other previously reported elements such as sodium, magnesium, aluminium, silicon, calcium and iron. It is bound in very large macromolecular compounds similar to the insoluble organic matter found in carbonaceous chondrite meteorites that have fallen to Earth, but with a major difference: there is much more hydrogen found in the comet's samples than in meteorites.

But as this kind of meteorite is associated with reasonably well-processed parent bodies such as asteroids, it is reasonable to assume that they lost their hydrogen due to heating. By contrast, comets must have avoided such significant heating to retain their hydrogen, and therefore must contain more primitive material.

From analyses of meteorites and laboratory simulations, the team was also expecting to identify a wide diversity of organic material in Comet 67P/C-G, ranging from very small molecules to heavy (or 'high molecular weight') organics.

Although Rosetta's ROSINA and Philae's PTOLEMY and COSAC instruments detected numerous low-molecular weight volatile organic molecules, COSIMA only saw very large carbon-bearing macromolecules in the dust particles, with nothing in between. This suggests potentially different sources for the lightweight volatile and heavier refractory carbonaceous material detected in the comet.

Rosetta comet flyby. Image Credit: ESA

"Although we cannot know if the organics seen in these dust particles were created in the interstellar medium before the protoplanetary nebula came together, or in the protoplanetary disk during early Solar System formation, COSIMA's dust grains are certainly witnesses to early formation processes, including that of the comet itself," says Nicolas Fray, first author of the paper.

"These particles have remained pristine and untouched for billions of years until they were released in the days or weeks before being 'caught' by COSIMA," adds Martin Hilchenbach, principal investigator of COSIMA. "The results add to the growing picture that Comet 67P/C-G contains some of the most primitive material from our Solar System's early history."

Using ESO’s Very Large Telescope and Hubble Space Telescope and other telescopes a fossilised remnant of the early Milky Way harbouring stars of hugely different ages has been revealed by an international team of astronomers. This stellar system resembles a globular cluster, but is like no other cluster known. It contains stars remarkably similar to the most ancient stars in the Milky Way and bridges the gap in understanding between our galaxy’s past and its present.

Terzan 5, 19 000 light-years from Earth in the constellation of Sagittarius (the Archer) and in the direction of the galactic centre, has been classified as a globular cluster for the forty-odd years since its detection. Now, an Italian-led team of astronomers have discovered that Terzan 5 is like no other globular cluster known.

The unusual cluster Terzan 5

The team scoured data from the Multi-conjugate Adaptive Optics Demonstrator [1], installed at the Very Large Telescope, as well as from a suite of other ground-based and space telescopes [2]. They found compelling evidence that there are two distinct kinds of stars in Terzan 5 which not only differ in the elements they contain, but have an age-gap of roughly 7 billion years [3].

The ages of the two populations indicate that the star formation process in Terzan 5 was not continuous, but was dominated by two distinct bursts of star formation. “This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive. At least 100 million times the mass of the Sun,” explains Davide Massari, co-author of the study, from INAF, Italy, and the University of Groningen, Netherlands.

The location of the star cluster Terzan 5

Its unusual properties make Terzan 5 the ideal candidate for a living fossil from the early days of the Milky Way. Current theories on galaxy formation assume that vast clumps of gas and stars interacted to form the primordial bulge of the Milky Way, merging and dissolving in the process.

“We think that some remnants of these gaseous clumps could remain relatively undisrupted and keep existing embedded within the galaxy,” explains Francesco Ferraro from the University of Bologna, Italy, and lead author of the study. “Such galactic fossils allow astronomers to reconstruct an important piece of the history of our Milky Way.”

Around the star cluster Terzan 5

While the properties of Terzan 5 are uncommon for a globular cluster, they are very similar to the stellar population which can be found in the galactic bulge, the tightly packed central region of the Milky Way. These similarities could make Terzan 5 a fossilised relic of galaxy formation, representing one of the earliest building blocks of the Milky Way.

This assumption is strengthened by the original mass of Terzan 5 necessary to create two stellar populations: a mass similar to the huge clumps which are assumed to have formed the bulge during galaxy assembly around 12 billion years ago. Somehow Terzan 5 has managed to survive being disrupted for billions of years, and has been preserved as a remnant of the distant past of the Milky Way.

Zooming on the star cluster Terzan 5

“Some characteristics of Terzan 5 resemble those detected in the giant clumps we see in star-forming galaxies at high-redshift, suggesting that similar assembling processes occurred in the local and in the distant Universe at the epoch of galaxy formation,“ continues Ferraro.

Hence, this discovery paves the way for a better and more complete understanding of galaxy assembly. “Terzan 5 could represent an intriguing link between the local and the distant Universe, a surviving witness of the Galactic bulge assembly process,” explains Ferraro while commenting on the importance of the discovery. The research presents a possible route for astronomers to unravel the mysteries of galaxy formation, and offers an unrivaled view into the complicated history of the Milky Way.

Notes:

[1] The Multi-Conjugate Adaptive Optics Demonstrator (MAD) is a prototype multi-conjugate adaptive optics system which aims to demonstrate the feasibility of different MCAO reconstruction techniques in the framework of the E-ELT concept and the second generation VLT Instruments.

[2] The researchers also used data from the Wide Field Camera 3 on board the NASA/ESA Hubble Space Telescope and NIRC2 (the Near-Infrared Camera, second generation) at the W. M. Keck Observatory.

[3] The two detected stellar populations have ages of 12 billion years and 4.5 billion years respectively.

More information:

This research was presented in a paper entitled “The age of the young bulge-like population in the stellar system Terzan 5: linking the Galactic bulge to the high-z Universe”, by F. R. Ferraro et al., which will be published in the Astrophysical Journal.

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

The Soyuz TMA-20M spacecraft is seen as it lands with Expedition 48 crew members NASA astronaut Jeff Williams, Russian cosmonauts Alexey Ovchinin, and Oleg Skripochka of Roscosmos near the town of Zhezkazgan, Kazakhstan on Wednesday, Sept. 7, 2016 (Kazakh time). Williams, Ovchinin, and Skripochka are returning after 172 days in space where they served as members of the Expedition 47 and 48 crews onboard the International Space Station. Image Credits: NASA/Bills Ingalls.

NASA astronaut and Expedition 48 Commander Jeff Williams returned to Earth Tuesday after his U.S. record-breaking mission aboard the International Space Station.

Williams and his Russian crewmates Alexey Ovchinin and Oleg Skripochka, of the Russian space agency Roscosmos, landed in their Soyuz TMA-20M at 9:13 p.m. EDT southeast of the remote town of Dzhezkazgan in Kazakhstan (7:13 a.m. Sept. 7, local time).

Expedition 48 landing site. Image Credit: NASA TV

Having completed his fourth mission, Williams now has spent 534 days in space, making him first on the all-time NASA astronaut list. Skripochka now has 331 days in space on two flights, while Ovchinin spent 172 days in space on his first.

“No other U.S. astronaut has Jeff’s time and experience aboard the International Space Station. From his first flight in 2000, when the station was still under construction, to present day where the focus is science, technology development and fostering commercialization. Jeff even helped prepare the space station for future dockings of commercial spacecraft under NASA’s Commercial Crew Program,” said Kirk Shireman, ISS Program manager at NASA’s Johnson Space Center in Houston. “We’re incredibly proud of what Jeff has accomplished off the Earth for the Earth.”

Williams was instrumental in preparing the station for the future arrival of U.S. commercial crew spacecraft. The first International Docking Adapter was installed during a spacewalk by Williams and fellow NASA astronaut Kate Rubins Aug. 19. Outfitted with a host of sensors and systems, the adapter’s main purpose is to connect spacecraft bringing astronauts to the station in the future. Its first users are expected to be Boeing’s CST-100 Starliner and SpaceX’s Crew Dragon spacecraft, now in development in partnership with NASA.

During his time on the orbital complex, Williams ventured outside the confines of the space station for a second spacewalk with Rubins to retract a spare thermal control radiator and install two new high-definition cameras.

The crew members also welcomed five cargo spacecraft during their stay. Williams was involved in the grapple of Orbital ATK’s Cygnus spacecraft in March, the company's fourth commercial resupply mission, and SpaceX’s eighth Dragon spacecraft cargo delivery in April, and welcomed a second Dragon delivery in July. Two Russian ISS Progress cargo craft also docked to the station in April and July delivering tons of supplies.

Expedition 49 continues operating the station with Anatoly Ivanishin of Roscosmos in command. He, Rubins, and Takuya Onishi of the Japan Aerospace Exploration Agency, will operate the station for more than two weeks until the arrival of three new crew members.

Shane Kimbrough of NASA and cosmonauts Sergey Ryzhikov and Andrey Borisenko of Roscosmos are scheduled to launch Sept. 23, U.S. time, from Baikonur, Kazakhstan.

mardi 6 septembre 2016

Image above: The Soyuz TMA-20M spacecraft is seen slowly departing away from the International Space Station. Image Credit: NASA TV.

NASA astronaut Jeff Williams and cosmonauts Alexey Ovchinin and Oleg Skripochka of Roscosmos undocked from the International Space Station at 5:51 p.m. EDT to begin their trip home. Ovchinin, the Soyuz commander, is at the controls of the Soyuz TMA-20M spacecraft.

Expedition 48 Crew Undocks from ISS for Return Trip to Earth

The crew is scheduled to land at 9:13 p.m. southeast of Dzhezkazgan, Kazakhstan.

The Expedition 49 crew members, Commander Anatoly Ivanishin of Roscosmos, NASA astronaut Kate Rubins, and astronaut Takuya Onishi of the Japan Aerospace Exploration Agency will operate the station for more than two weeks until the arrival of three new crew members.

NASA TV will air live coverage of the Soyuz TMA-20M deorbit burn and landing beginning at 8 p.m. Watch live at http://www.nasa.gov/ntv.

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